KR101630553B1 - Method for operating a drive assembly and dfrive assembly - Google Patents

Abstract

The present invention relates to a gasoline engine (1) and a method for operating a drive assembly with an exhaust gas cooling system. In the above method, the combustion air supplied to the cylinder 3 of the gasoline engine 1 through the intake valve is compressed by the exhaust gas turbocharger 12 having the turbine 13 having the variable turbine structure. The inlet valve is closed before the piston in the cylinder 3 reaches the bottom dead center. The exhaust gas supplied to the turbine is cooled in a part of the exhaust gas line, in particular in an exhaust gas manifold.

Description

≪ Desc / Clms Page number 1 > METHOD FOR OPERATING A DRIVE ASSEMBLY AND DFRIVE ASSEMBLY,

The invention relates to a method for operating a drive assembly comprising a feature according to the preamble of claim 1. The present invention also relates to a drive assembly comprising a feature according to the preamble of claim 10.

This patent application claims priority from German Patent Application DE 10 2011 122 442.8 dated December 24, The disclosure of which is incorporated herein by reference.

Driving assemblies for driving automobiles, which are typically implemented as internal combustion engines in automobiles, for example passenger cars or commercial vehicles, are used. Internal combustion engines are typically gasoline engines or diesel engines. In order to reduce the fuel consumption and exhaust emission of automobiles and to improve the performance and comfort of the automobile, improvement of the internal combustion engine related to this has been proposed in the past.

DE 101 59 801 A1 relates to an internal combustion engine comprising, for example, at least one supercharging device driven by the exhaust gas flow of an internal combustion engine and a camshaft adjustable according to a Miller-cycle. Other compressor stages are arranged in series or parallel to the supercharging device, and the compressor stages are not driven by the exhaust gas flow of the internal combustion engine. When the revolution speed of the internal combustion engine is low, the boost pressure is increased by activation of other compressor stages. Other compressor stages which are not driven by the exhaust gas flow of the internal combustion engine can be electrically driven, for example. Such an electrically driven compressor stage is also referred to as an electric booster.

The Miller-Cycle is disclosed in US 2,670,595. A description of the Miller-Cycle is provided in the article "Miller-Cycle and Aktinson-Cycle of a Supercharged Diesel Engine" (E. Schutting et al., 2007, No. 6, pages 480-485) of the Technical Motor Journal . In order to supply air to the cylinder, the inlet valve is opened after the exhaust stroke in accordance with the Miller-Cycle. Before the piston reaches the bottom dead center of the inlet stroke, the inlet valve is closed.

EP 2 041 414 B1 relates to a method for operating a gasoline engine in which at least one inlet valve of a gasoline engine is closed prematurely or very late, wherein the combustion air flow fed to the gasoline engine is fed by a supercharger Compressed. A partial flow of the recycled exhaust gas is supplied to the combustion air flow as exhaust gas recirculation at least at full load and the gasoline engine is operated at a structural compression ratio greater than 1:10.

DE 102 33 256 A1 relates to a method for igniting a fuel-air mixture in a fuel direct injection gasoline engine comprising a spark ignition part in a preliminary chamber and a preliminary chamber. The reserve chamber is operatively associated with a small piston recess.

The thermodynamic efficiency of gasoline engines is limited due to the throttling required for quantitative load control and the reduced compression ratio to prevent engine knock. The way to maximize the throttling and structural compression ratio during partial load operation is the Miller-Cycle described above and the Atkinson-cycle disclosed in the prior art. In this case, air efficiency and effective compression are reduced by premature or delayed closing of the inlet valve. Air efficiency refers to the air supply change quality and represents the ratio between the actual air volume supplied to the cylinder during the intake stroke and the theoretical maximum air volume. As a result, the engine is de-throttled, and the compression final temperature and knocking tendency are reduced. In addition, structural compression can be increased. However, the Miller / Atkinson-cycle disclosed in the prior art contains significant performance losses.

An object of the present invention is to improve the efficiency of a gasoline engine without deteriorating the performance of the engine.

This object is achieved by a method for operating a drive assembly with a gasoline engine according to claim 1 and a drive assembly with a gasoline engine according to claim 10.

The dependent claims define preferred embodiments and / or improvements of the present invention.

A method for operating a drive assembly having a gasoline engine and an exhaust gas cooling system in accordance with the present invention is provided. The gasoline engine is a high compression gasoline engine in the preferred embodiment. A preferred embodiment is a supercharged or high compression gasoline engine. Preferably, the supplied combustion air is compressed in a cylinder of the gasoline engine to a structural compression ratio of greater than 1:10 and less than 1:20. Gasoline engines are especially direct-injection gasoline engines. In other words, in the preferred embodiment, the fuel is injected directly into the cylinder.

In the method according to the invention, the combustion air supplied to the cylinder of the gasoline engine through the inlet valve is compressed by an exhaust gas turbocharger having a turbine with a variable turbine structure. The exhaust gas supplied to the turbine is cooled in accordance with the invention, particularly at the portion of the exhaust line between the exhaust valve of the gasoline engine and the turbine of the exhaust turbocharger. Preferably, the exhaust gas is cooled in the exhaust gas manifold. The exhaust manifold is particularly preferably incorporated in the cylinder head of a gasoline engine.

Before the piston in the cylinder reaches the bottom dead center of the cylinder, the inlet valve is closed. The exhaust turbocharger preferably includes a turbine wheel and a compressor wheel, which are connected to each other at the shaft. The turbine wheel is driven by the exhaust gas flow of the gasoline engine. The compressor wheel is disposed in the combustion gas air supply of the gasoline engine and is driven by a turbine wheel connected through the shaft to compress the combustion air supplied to the cylinder of the gasoline engine. To this end, for example, an adjustable guide vane can be arranged in the turbine housing of the exhaust gas turbocharger in which the turbine wheel is arranged. By adjusting the setting of the guide vanes, the number of revolutions of the turbine wheel in the same exhaust gas flow can be changed, whereby the compression, so-called boost pressure, provided by the compressor wheel can be varied. Alternatively, the effective flow cross-section can be changed, for example, by a sliding sleeve. An exhaust gas turbocharger having a variable turbine structure preferably includes a radial turbine and a radial compressor. A guide vane analog may be disposed in the turbine wheel inlet, and the guide vane analog is controlled by an electric actuator. In this case, the effective flow cross-section can be changed before the turbine wheel by rotation of the guide vane.

Since the inlet valve is prematurely closed before the piston reaches the bottom dead point, the compression ratio of the gasoline engine can be increased, and engine knocking does not occur. The variability of the flow cross-section at the turbine inlet widens the available turbine map. The control of the turbine is made in particular dependent on the boost pressure required. As engine load increases, higher boost pressure is required. As the flow cross-section in the turbine is reduced to form the boost pressure, an increased turbine output is provided. In this case, in contrast to the use of diesel engines, the minimum turbine flow cross section is limited by the maximum permissible exhaust backpressure. The control is therefore distinguished from the control of the exhaust gas turbocharger by bypass flow regulation (waist-gate), since in this case such a restriction is basically unnecessary.

The use of an exhaust gas turbine with a variable turbine configuration extends the width of the available compressor map, so that a boost pressure sufficient to compensate for the charging loss that may occur due to the premature closure of the inlet valve at mid- have. Thus, a significant increase in the overall thermodynamic efficiency can be achieved, especially in this operating range. By closing the inlet valve prematurely, further cooling of the combustion air is achieved by expansion during the inflow stroke in the cylinder. This reduces compression operation, lowers the process temperature, and the lowered process temperature reduces knocking tendency and wall heat loss.

In addition, the exhaust gas temperature can be reduced in the method according to the present invention, thereby enabling the thermal design of the exhaust turbocharger to be as low as, for example, up to 850 DEG C for gasoline engines. This allows material selection and gap size design of the exhaust turbocharger of a gasoline engine similar to current diesel engines, thus reducing the cost of an exhaust gas turbocharger with a variable turbine structure. Also, the turbine efficiency can be improved due to the reduced gap size design. Thereby, a performance neutral efficiency improvement can be achieved unlike the gasoline engine which is operated according to the miller-combustion method with an exhaust gas turbocharger having a fixed turbine structure according to the present method.

According to an embodiment, the variable turbine structure of the exhaust gas turbocharger is adjusted depending on the load of the gasoline engine. The charge loss due to the early closure of the inlet valve can be appropriately compensated in the entire load range of the gasoline engine by expanding the compressor map of the exhaust gas turbocharger having the variable turbine structure by the adjustment of the variable turbine structure. In addition, the process temperature and exhaust gas temperature can be reduced, especially during full load operation, thereby improving the efficiency of the gasoline engine and enabling cheaper materials to be used in the turbine and exhaust gas branching devices of the exhaust gas turbocharger.

The combustion air supplied to the cylinder according to another embodiment is further compressed by an electric drive compressor, so-called electric booster or e-booster. The inlet valve is prematurely closed before the piston in the cylinder reaches the bottom dead point, so that the air efficiency decreases, that is, the ratio of the actual air amount supplied to the cylinder to the theoretical maximum air amount in the cylinder decreases. The reduced air efficiency can increase the response time of the gasoline engine especially to the demand for increased speed or moment. The combustion air is pre-compressed by the electric drive compressor, which accelerates the exhaust gas turbocharger so that the response time of the gasoline engine can be reduced by the electric drive compressor. The electric drive of the compressor has a power consumption of, for example, less than 1 kW, and thus is generally operable with a 12 V electrical system provided in the vehicle. The combination of an exhaust gas turbocharger and an electric drive compressor having a variable turbine structure also enables the electric drive compressor to be operated for the improvement of the response time of the gasoline engine and therefore measures to increase the electric output of the electric system of the vehicle .

A very wide compressor map can be achieved by a combination of a turbocharger and a compressor mechanically driven by a crankshaft provided in the group of embodiments. This causes the charging loss caused by the early closure of the inlet valve to be compensated for in the wide engine speed and load range of the gasoline engine. This allows a performance-neutral efficiency improvement of the gasoline engine over a wider load range of the gasoline engine.

According to an improvement of the present invention, the exhaust gas turbocharger's parallel connection valve can be adjusted depending on the load of the gasoline engine. The parallel connection valve allows a controlled amount of exhaust gas of the gasoline engine to pass through the turbine of the exhaust gas turbocharger. Such a parallel connection valve is referred to as a waste gate or bypass valve. A parallel connection valve allows a wide compressor map to be provided even in the full load range, especially when the rotational speed of the gasoline engine is high, whereby the compensation of the charge loss can be properly adjusted.

A gasoline engine according to another preferred refinement comprises an exhaust gas recirculation system, in which case the exhaust gas supplied by the exhaust gas recirculation system is cooled. Exhaust gas recirculation systems may include, for example, so-called high pressure exhaust gas recirculation systems and / or so-called low pressure exhaust gas recirculation systems. The high pressure exhaust gas recirculation system connects the exhaust gas system between the exhaust valve of the gasoline engine and the turbine of the exhaust turbocharger to the combustion air supply between the compressor and the inlet valve. The low pressure exhaust gas recirculation system connects the exhaust gas system behind the turbine of the exhaust gas turbocharger to the combustion air supply in front of the compressor. The combustion air supplied to the gasoline engine by the cooling system of the exhaust gas recirculation system can be cooled, so that the process temperature can be reduced. Exhaust gas recirculation may be implemented, for example, by using engine coolant, for example, using an integrated exhaust manifold. In particular, the exhaust gas cooling system of the recirculated exhaust gas may be the same as that acting on the exhaust gas supplied to the turbine of the exhaust gas turbocharger.

Particularly, in addition to the improvement of engine performance, an advantage of efficiency is provided. In this case, the current gasoline engine concept must further lower the process temperature by fueling in the cylinder to protect the exhaust gas guiding component from too high a heat load. This generally results in higher fuel consumption. By using an integrated exhaust manifold, this measure can certainly be reduced, and thus the efficiency of the engine in addition to engine performance can be improved by a few percentage points. Thus, unlike the use of conventional exhaust gas recirculation systems, the exhaust gas temperature can be reliably reduced by the integrated exhaust gas manifold.

The inlet valve can also be closed in the range of 35 to 90 degrees of the crankshaft angle of the gasoline engine before bottom dead center between the inlet stroke and the compression stroke. The inlet valve can be closed before the bottom dead center, in particular in the range of 50 to 70 degrees of the crankshaft angle of the gasoline engine. The closing of the inlet valve is related to the millimeter valve stroke, that is, the inlet valve is closed when the last valve stroke is less than or equal to 1 mm, in the aforementioned Frankshaft angle range. The combustion air supplied up to that time by the early closing of the inlet valve is expanded in the next process of the intake stroke, and thus the combustion air is cooled. As a result, the compression operation during the subsequent compression stroke is reduced, and the process temperature is lowered, so that the knocking tendency and the wall heat loss of the gasoline engine can be reduced. At the same time a complete expansion ratio is provided for the operating stroke.

According to another embodiment, the gasoline engine includes a variable valve control. The angle at which the inlet valve is closed is regulated by the variable valve control portion depending on the load of the gasoline engine. By adjusting the angle at which the inlet valve is closed, the air efficiency can be adjusted depending on the load, so that throttle-free adjustment of the engine load becomes possible, and this adjustment enables performance-neutral efficiency improvement.

In addition, or as an alternative, the exhaust gas between the exhaust valve of the gasoline engine and the exhaust gas turbocharger is cooled by cooling the exhaust manifold of the gasoline engine. Cooling the exhaust gases prior to the exhaust gas turbocharger allows thermal design of the exhaust gas turbocharger to be at a lower exhaust gas temperature, thus allowing for lower material selection and reduced gap size design.

In accordance with the present invention, there is also provided a drive assembly having a gasoline engine. The drive assembly includes an exhaust gas turbocharger with a turbine having a variable turbine structure and a valve control. An exhaust gas turbocharger is formed for compression of the combustion air supplied through the inlet valve to the cylinder of the gasoline engine. The valve control portion is formed to close the inlet valve before the piston in the cylinder particularly reaches the bottom dead point between the inlet stroke and the compression stroke. Thus, the gasoline engine is particularly suited for the implementation of the above-described method with one or more of the features described above, and thus also includes the advantages described above. Particularly, the gasoline engine makes it possible to improve the efficiency as compared with the conventional gasoline engine. In this case, the performance of the gasoline engine is not reduced by the improvement of the efficiency.

According to the invention, the drive assembly comprises an exhaust gas cooling device for cooling the exhaust gas supplied to a part of the exhaust gas line of the turbine, said cooling device being assigned to a part of the exhaust gas line. A portion of the exhaust line in the group of embodiments is an exhaust manifold. The exhaust manifold is preferably partially or (particularly preferably) fully integrated into the cylinder head of a gasoline engine.

The exhaust manifold, which is typically implemented separately in the integrated exhaust gas manifold, is fully integrated within the cylinder head, and the only pipe connection to the turbine after withdrawal from the cylinder head is maintained. In order to prevent the component temperature from becoming unacceptably high, the profile guiding the gas is implemented to be cooled and cleaned. This coolant jacket may be formed by a foundry core comprising a plurality of parts. The coolant can be water in particular.

The drive assembly according to the invention may comprise a gasoline engine having a structural compression ratio of 1:10 to 1:20, preferably 1:12 to 1:15, in particular 1:13. This large compression ratio is possible because the early closing of the inlet valve regulates the air efficiency of 1 < &apos; &apos;, which can prevent the knocking tendency of the gasoline engine. The air efficiency is adjusted to, for example, 0.5 to 0.9, preferably 0.6 to 0.8.

According to the present invention there is provided an automobile, especially a railless ground vehicle, having the aforementioned drive assembly including a gasoline engine. The improved efficiency of gasoline engines can reduce fuel economy and emissions of automobiles, especially CO ₂ emissions. Since the above-mentioned efficiency enhancement can be performed in a performance neutral manner, the user of the automobile is not affected by the performance loss in the operation of the automobile.

Preferred embodiments of the present invention will be described in detail below with reference to the drawings.

1 is a schematic diagram of a drive assembly with a gasoline engine according to an embodiment of the invention.
2 is another schematic view of a drive assembly having a gasoline engine according to another embodiment of the present invention;
3 is a schematic view showing a motor vehicle according to an embodiment of the present invention.

In a typical gasoline engine, the thermodynamic efficiency is limited due to the reduced throttle required for quantitative load control and the reduced compression ratio to prevent engine knocking. The so-called Miller-Cycle or Atkinson-Cycle is a way to increase throttleling and structural compression ratio as much as possible during partial load operation. In this case, by early or delayed closing of the inlet valve (early closing of the inlet valve FES, delayed closing of the inlet valve SES) air efficiency and effective compression are reduced. This causes the engine to be throttled, the compression final temperature and knocking tendency to decrease, or the structural compression to increase. The air efficiency, which represents the ratio of the actual air volume to the maximum theoretical air volume after the inflow stroke, can be reduced by a Miller-Cycle from, for example, 0.95 to 0.5 to 0.9. However, reduced air efficiency can result in performance losses. In order to prevent such a performance loss and still achieve an efficiency improvement by the Miller-Cycle, an exhaust gas turbocharger having a variable turbine structure and a gasoline engine having a high compression miller-cycle are proposed according to an embodiment of the present invention. To achieve a high compression miller-cycle, the inlet valve is closed before the piston in the cylinder reaches the bottom dead center. The inlet valve may be closed, for example, in the range of 90 to 35 degrees of the crankshaft angle before reaching bottom dead center. Preferably the inlet valve can be closed in the range of 70 to 50 degrees of the crankshaft angle before reaching bottom dead center.

Figure 1 shows an embodiment of a drive assembly with a gasoline engine (1). The gasoline engine 1 is preferably a spark ignition engine. The gasoline engine 1 includes a cylinder block 2 having four cylinders 3 shown schematically. Combustion air is supplied through inlet valves (not shown) on the inlet side 4 of the gasoline engine 1. Since the inlet valve may include a variable valve train, the crankshaft angle that closes the inlet valve may be variably controlled. The gasoline air supplied to the inflow side 4 contains combustion exhaust gas 6 which is mixed with the fresh air 5 and the fresh air 5 by the exhaust gas recirculation system 7,8. The fresh air (5) is mixed with the exhaust gas (6) through the low pressure exhaust gas recirculation system (8) by an adjustable low pressure exhaust gas recirculation valve (9). Further, the exhaust gas supplied through the low-pressure exhaust gas recirculation system 7 is cooled by the cooling device 18. This mixture is compressed by an electric drive compressor, the so-called e-booster. The e-booster includes a compressor (10) driven by an electric motor (11). The compression by the compressor 10 can be variably controlled by the control unit (not shown) of the electric motor 11.

In this embodiment, the air compressed by the compressor 10 is supplied to an exhaust gas turbocharger 12 having a variable turbine structure. The exhaust gas turbocharger 12 includes a turbine 13 and a compressor 14 that are driven by the exhaust gas of a gasoline engine 1 and are connected to each other through a hollow shaft 15. Other exhaust gases on the exhaust side 16 of the gasoline engine 1 can be supplied to the combustion air compressed by the compressors 10 and 14 through the high pressure exhaust gas recirculation system 7. [ A high pressure exhaust gas recirculation system (7) includes a high pressure exhaust gas recirculation valve (17) for regulating exhaust gas recirculation by a high pressure exhaust gas recirculation system (7). The combustion air compressed thereby and mixed with the exhaust gas is supplied to the inlet side (4) through the boost air cooling device (19). The exhaust gases from the four cylinders 3 from the exhaust side 16 are collected in an exhaust gas manifold 20 and supplied to a high pressure exhaust gas recirculation system 7 and a turbine 13 having a variable structure. The exhaust gas manifold 20 for cooling the exhaust gas may include an exhaust gas cooling device 21 that is cooled with, for example, cooling water.

The exhaust gas turbocharger 12 also includes an optional parallel connection valve 22 which allows an adjustable amount of exhaust gas of the gasoline engine 1 to be supplied to the turbine 13 of the exhaust gas turbocharger 12 &Lt; / RTI &gt; On the downstream side of the turbine 13, the gasoline engine 1 includes an exhaust gas purifying system 23, for example a three-way catalytic converter. The gasoline engine 1 also includes a gasoline injection system, preferably a gasoline direct injection system that injects the fuel directly into the cylinder 3.

Based on the supercharged gasoline engine 1 including, for example, a gasoline direct injection system, the valve train variability is regulated by volume efficiency with respect to phase, control width and cylinder cutoff for adjusting the engine load without throttling. At the same time, the cylinder block 2 of the gasoline engine 1 has an increased structural compression ratio of, for example, about 12-14. At the same time, in order to reduce the knocking tendency increased during higher partial load- and full-load operation, the air efficiency is regulated, for example by 0.5 to 0.9 or preferably 0.6 to 0.8, by the early closing (FES) of the inlet valve. Further, the exhaust gas cooled and converted in the operating state in which the boost pressure is generated is recirculated through the low-pressure exhaust gas recirculation system 8 to increase the specific heat capacity of the exhaust gas. As shown in FIG. 1, the exhaust gas is removed after the catalytic converter 23 by the low pressure exhaust gas recirculation system 8, filtered, cooled, and recirculated before the compressors 10, 14. The resulting charging loss is compensated for by an increase in the intake manifold pressure by the compressors 10, 14. Basically, part of the compression of the working gas at the position in the cylinder is thereby carried out by the compressors 10, 14. Recirculation cooling of the compressed working gas is effected by means of a correspondingly dimensioned supercharged air cooling device 19 before the remaining compression in the cylinder 3 is effected. Further cooling of the working gas by inflow in the cylinder (3) by the FES or by expansion during the intake stroke is achieved. As a result, the compression operation is reduced, the process temperature is reduced, and the reduced process temperature reduces wall heat loss and knocking tendency in the cylinder block 2. At the same time, the complete expansion ratio of the structural compression ratio is used during the operating stroke. The increased required cooling power for boost air cooling and exhaust gas recirculation cooling is largely compensated by reduced heat transfer into the engine coolant.

An exhaust gas turbocharger 12 having a variable turbine structure for supercharging the gasoline engine 1 is used in combination with the e-booster 10, 11. Unlike a common exhaust gas turbocharger with a parallel connection valve 22, the variable turbine structure of the turbine 13 and the variable turbine map width associated therewith provide a boost pressure sufficient to compensate for the charging loss due to the above- Can be formed. Further, the total flow rate of the exhaust gas can be guided through the turbine, thereby providing more turbine output in the full load range. This results in a significant improvement in the overall thermodynamic efficiency, especially in the operating range associated with the cycle. The reduced process temperature and the preferred cooling system 21 of the exhaust manifold 20 allow the exhaust gas turbocharger 12 to be designed for thermal gasoline combustion processes, for example at exhaust gas temperatures as low as 850 ° . This enables cheaper material selection and gap size design than the concept of a common exhaust turbocharger with a variable turbine structure for gasoline engines. The cost of the exhaust gas turbocharger can be reduced by material selection, and a reduced gap size design can achieve higher turbine efficiency compared to a common exhaust gas turbocharger for a gasoline engine.

In summary, the above-described operating process is based on the internal expansion at the early closing (FES) of the inlet valve, i.e., the process temperature, which is reduced by the cooled precompression, the cooled exhaust gas recirculation, the increased structural compression ratio, Resulting in a reduced exhaust gas temperature upon opening of the valve. Thus, the combination of the above-described operating method (high compression miller-cycle) and exhaust gas turbocharger with a variable turbine structure is advantageous in that it is economically and technically feasible to use an exhaust gas turbocharger having a variable turbine structure It is crucial to improve performance neutral efficiency at low exhaust gas temperatures and high compression miller-cycle.

Fig. 2 shows another embodiment of a gasoline engine 1 suitable for, for example, a higher output per liter. The drive assembly with the gasoline engine 1 of FIG. 2 may include a turbocharger 212 having a fixed turbine configuration instead of the turbocharger 12 having a variable turbine configuration. That is, the exhaust gas turbocharger 212 includes a turbine 213 having a fixed turbine structure. The exhaust gas turbocharger 212 also includes a parallel connection valve 222, which is also referred to as a bypass valve or a waste gate. As an alternative, the drive assembly may include an exhaust gas turbocharger 212 connected to the compressor 214 via a shaft 215 and having a variable turbine configuration. 2, the gasoline engine 1 of Fig. 2 comprises a mechanically driven compressor 210 instead of the e-booster 10, 11, which is driven by a drive device 211 Is connected to the crankshaft of the gasoline engine 1, and is driven by the crankshaft. This concept of a mechanically driven compressor 210 and an exhaust gas turbocharger 212 is also referred to as a twin charger concept. The remaining components of the gasoline engine of FIG. 2 correspond to the components of the gasoline engine of FIG. The inlet valve of the gasoline engine 1 is closed before the piston reaches the bottom dead center. As a result, the gasoline engine 1 of Fig. 2 also operates according to the Miller-cycle.

Unlike typical gasoline engines, the reduction in exhaust gas temperature described above with reference to FIG. 1 in reducing air efficiency results in a reduction in exhaust gas enthalpy, and the exhaust gas turbocharger is configured to change the exhaust gas enthalpy to a transition operation state For natural load demands. In today's common gasoline engine concept, the increase in exhaust gas enthalpy is achieved by further adjustment of ignition angle and combustion. This results in loss of efficiency in operation of the transition engine. (E. G., E-booster 10 or 11 shown in Figure 1 or mechanically driven compressor 210 shown in Figure 2) to improve the response time of the gasoline engine resulting from reduced air efficiency ) Are integrated into the supercharging system. The preliminary compressor is disposed in front of the main compressor (14 or 214) in the intake path after the air filter. The exhaust gas turbocharger 12 or 212 is accelerated by the formation of a pressure ratio of less than 1.5 hPa and thus a predetermined response time is achieved. In the case where the engine is smaller, the drive output of the e-booster 10, 11 is sufficient in a range smaller than 1000 W, that is, the electric machine 11 is operated by the electric energy of the 12 V electric system provided for at least a short time. If the engine is larger, the electrical output of the 12 V electrical system is usually not sufficient. In this case, a mechanically driven preliminary compressor 210 is preferred and the preliminary compressor is mechanically driven by the crankshaft of the gasoline engine 1.

3 shows an automobile 300 according to an embodiment of the present invention including the above-described drive assembly with a gasoline engine 1.

1: gasoline engine 2: cylinder block
3: cylinder 6: combustion exhaust gas
7, 8: Exhaust gas recirculation system 9: Low pressure exhaust gas recirculation valve
10, 14: Compressor 11: Electric motor
12, 212: Exhaust gas turbocharger 13: Turbine
18: Cooling unit 20: Exhaust gas manifold
210: Compressor 300: Automobile

Claims (15)

1. A method for operating a drive assembly having a gasoline engine (1)
Compressing the combustion air supplied into the cylinder (3) of the gasoline engine (1) through an intake valve by an exhaust gas turbocharger (12); And
Closing the inlet valve before the piston in the cylinder (3) reaches bottom dead center,
The use of an exhaust gas turbocharger 12 having a turbine 13 with variable flow cross section and the use of exhaust gas supplied to the turbine 13 at the portion of the exhaust gas line comprising the exhaust gas cooling device 21 Lt; / RTI &gt; The method according to claim 1, characterized in that the exhaust gas is cooled in the exhaust gas manifold (20). 3. A method according to claim 1 or 2, characterized in that an exhaust gas manifold (20) is used for cooling the exhaust gas, and the exhaust gas manifold is integrated into the cylinder head of the gasoline engine . 3. A method as claimed in claim 1 or 2, characterized in that the variable turbine structure of the exhaust gas turbocharger (12) is regulated depending on the load of the gasoline engine (1). 3. Method according to claim 1 or 2, characterized in that the combustion air (5) supplied to the cylinder is further compressed by the electric drive compressor (10). 3. A method as claimed in claim 1 or 2, characterized in that the inlet valve is closed in the range of 35 [deg.] To 90 [deg.] Of the crankshaft angle of the gasoline engine (1) before bottom dead center. 3. A method according to claim 1 or 2, characterized in that the gasoline engine (1) comprises a variable valve control and the angle at which the inlet valve is closed is regulated depending on the load of the gasoline engine (1). 3. A method as claimed in claim 1 or 2, characterized in that fuel is injected directly into the cylinder (3). 3. A method as claimed in claim 1 or 2, characterized in that the supplied combustion air is compressed in the cylinder (3) of the gasoline engine (1) to a structural compression ratio greater than 1:10 and less than 1:20. A drive assembly for carrying out the method according to claim 1,
- Gasoline engine,
- an exhaust gas turbocharger (12) for compressing the combustion air supplied through the inlet valve into the cylinder (3) of the gasoline engine (1)
- a valve control configured to close the inlet valve before the piston in the cylinder (3) reaches bottom dead center,
In order to cool the exhaust gas supplied to the turbine 13 in the portion of the exhaust gas line and the exhaust gas turbocharger 12 having the turbine 13 whose flow cross section is variable, Characterized in that an assigned exhaust gas cooling device (21) is provided. 11. The drive assembly of claim 10, wherein the portion of the exhaust gas line is an exhaust gas manifold (20). 12. The drive assembly of claim 11, wherein the exhaust manifold (20) is integrated into a cylinder head of a gasoline engine. 13. The drive assembly according to any one of claims 10 to 12, characterized in that the gasoline engine (1) has a structural compression ratio of greater than 1:10 and less than 1:20. 14. The drive assembly of claim 13, wherein the gasoline engine (1) has a structural compression ratio of greater than 1:12 and less than 1:15. An automobile having a drive assembly according to any one of claims 10 to 12.

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